It is known that in a general single-lens reflex camera a depth of field can be varied by changing a stop of lens. However, in a small image pickup device such as a cellular phone and the like there is a case that the stop cannot be equipped due to a problem of cost or size.
Then, in recent years a technique which is called as a light field (light irradiating field) camera is gained attention. In the case of using the light field camera, a depth of field of image data can be changed after imaging. For example, the technique concerning the light field camera is described in patent literature 1 to patent literature 3 and the like. The light field camera is the technique of reconstructing the image data which is acquired by using a plenoptic camera to generate a refocused image data